Control knob and shaft connection



Feb. 23, 1954 GREEN 2,670,227

CONTROL KNOB AND SHAFT CONNECTION Filed Oct. 28, 1949 /0 {I41 I I? INVENTOR. George K. Gree/z BY c222 poses.

control knob when the shaft.

,the spring in the socket. For a more complete understanding of the in- Patented Feb. 23, 1954 2,670,227 ICE CONTROL KNOB George K. Green,

New York AND SHAFT CONNECTION Henrietta, N. Stromberg-Carlson Compan Y., assignor to a corporation of Application October 28, 1949, Serial No. 124,209

6 Claims. (Cl. 28753) This invention relates to retaining springs, more particularly to springs for firmly retaining a control knob on a shaft during ordinary usage while permitting ready removal of the control knob by the exertion of an axial force of greater than normal magnitude, and the invention has for an object the provision of improved springs of this character.

In various types of apparatus, such as radio receivers, for example, the control shafts which extend through apertures in the cabinet are provided with control knobs which must be removed from the shafts in the event it becomes necessary to remove the controlled apparatus, such as the receiver chassis, from the cabinet for repair pur It is desirable, therefore, not only that the control knobs be firmly positioned on the shafts during ordinary usage so that there will be no rocking or slipping of the knobs on the shafts, but also that the knobs be readily removable. The use of set screws has been found generally unsatisfactory and various expedients have been proposed for causing the knobs to be frictionally held on the shafts by means of springs or similar resilient elements while permitting axial removal of the knobs merely by the exertion of abnormal axial forces. Such expedients have not in most cases been entirely satisfactory, and it is accordingly a further object of the invention to provide knob retaining spring structure which is effective securely to hold the knob on the shaft, which may be readily manufactured at low cost, which is adaptable to various existing knob constructions, and which is effective to retain itself in the socket of the knob is removed from the In carrying out the invention in one form, a retaining spring is provided which comprises a pair of elongate arms of curvilinear cross section, each having an open side, and a connector member extending therebetween for supporting the arms in spaced parallel relation. The relation of the connector member to the armsis such that one of the edges defining the open sides of the arms is disposed at a different level than the other edges of the open sides. Accordingly when the spring is positioned within the shaft receiving socket of a control knob the lowermost edges of the armswill engage a flat surface of the socket and the other edges of the arms will be free of the surface to permit transverse fiexure of the arms when the upper surfaces thereof are engaged by a surface of the control shaft. It is preferably the rear edge of each open side that is disposed at a lower level, and accordingly when the knob is withdrawn from the shaft these lower edges of the arms tend to bite into thelsurface of the shaft receiving socket; therebyto retain 2 vention reference should now be had to the drawing, in which:

Fig. 1 is a plan view of a spring embodying the present invention, on a greatly enlarged scale;

Fig. 2 is a side elevational view of the spring shown in Fig. 1;

Fig. 3 is an elevational sectional viewtaken through a conventional control knob and showing the spring of F'gs. 1 and 2 located therein before the knob is positioned on a shaft;

Fig. 4 is an elevational cross-sectional view similar to Fig. 3 but showingthe control knob positioned on the end of a shaft; and

Fig. 5 is a rear elevational view of the control knob of Figs. 3 and 4 showing the shaft in cross section.

Referring now to the drawing, the invention is shown as embodied in a spring I0 formed of suit able spring material such, for example, as spring steel or bronze, and adapted to be employed for positioning a control knob II on a control shaft I2. As shown, the spring I0 is formed to provide a pair of elongate arms I3 and I4 which are substantially curvilinear or V-shaped in cross section to provide open sides respectively defined by a pair of forward edges I5 and I6 and a pair of rear edges I1 and I8. These edges are preferably substantially parallel to each other, and arms I3 and I4 preferably extend transversely of shaft I2. Formed integrally with the arms I3 and I4 and extending therebetween is a connector member I9, the arms l3 and I4 being respectively cut away, as shown in Fig. 1, so that the connector member I9 engages each of the arms at a point adjacent the respective rear edges I 1 and I8. The connector member I9 serves to maintain the arms I3 and I4 in substantially parallel relation with the rearward edges I7 and I8 at a lower level than the forward edges I 5 and I6.

The control knob l I, as shown in Figs. 3 and 5, has a rearwardly facing hub portion 20 in which is formed a shaft receiving socket 2i having at least one substantially flat side wall surface 22 adapted to be engaged by the spring I!) when the spring is inserted into the socket and, as shown in Fig. 3, the spring I 0 rests in the socket 2! prior to insertion. of the shaft I2 thereinto with the open sides of arms I3 and I4 facing, and with the rear edges I "I and I8 engaging, the flat socket surface 22 and provided, in accordance with conventional practime; wi a fia't ur ace 23 which is adapted t engage the apices of the spring arms I'3 and I 4 maintaining, said arms in 3 and cause the arms to flex transversely, whereby the upper -surfaces-ofthe shaft.- LZ .areheld in frictional. engagement with the. corresponding upper surfaces of the socket 2 l, as shown best in Fig. 5.

Since the forward edges [5 and iii of the arms l3 and M are in spaced relation to the socket surface 22, substantially all of the spring pres.- sure will be exerted through therear edges. ll. and it of the arms 13 and [4, thus causing these rear edges to tend to bite into the surface 22, thereby effectively to retain the spring in the socket 2| when the control knob is withdrawn.

from the end of the shaft. By reason of the two-point engagement ofthe spring [0 with the shaft and socket surfaces 22' and 23, the knob will .be firmly held against rocking'movementton the shaft and yet may be readily removed from the shaft merely by'the exertion of'an abnormal axial pull on the knob, the biting action. of the forward edges l1 and lfl'of the spring serving, as heretofore. mentioned, to. retainthe spring in the .socket 21..

While a particular embodiment of the'invention has been shown, it will beunderstood, of course, that the invention is not limited thereto since many modifications may be made, and'it is therefore contemplated by .the appended claims to cover any such modifications as fall within the true spirit and scope of the invention.

What is claimedand desired to be secured by Letters Patent is:

.1. In combination, a control knob having a shaft receiving socket including a flat side wall surface, ashaft received in said socketand having a flat surface facing said flat socket surface, and spring, means engaging said surfaces comprising a pair of elongate. arms of curvilinear cros section extending transversely of said, shaft, each of said arms having. an Open side facing said socket. surface and anapex engaging said shaft surface,,and a. connector member extending, between. and interconnecting, said, arms longitudinally of saidshaft. for maintaining said arms in spaced relation suchthat certain of the edges of said arms. are substantialhrparallel to each other. I

2. In combination, a control knob having a shaft receiving socket including a fiat side wall surface,.a shaftv received in said socket and having a flat surface facing said flat. socket. surface, and. spring means. engaging said surfaces comprising a pair of elongate arms extendingtransversely of. said shaft and of substantially V- cross section with the opened sides of said arms facingsaidsocket surface, and a con.- nector member extending between and interconnesting said arms for maintaining said arms in spaced relation such that certain of the edges of said open sides are substantially parallel to each other, said shaft surface engaging the apices of said arms to flex. said arms transversely .upon insertion of said sha'ftinto said socket.

3.1m combination, .a control knob having a .sha'ftreceiving socket. including afiat side-wall surface, a shaft receivedin said socket and having a flat surface facing .said flat, socket surface, and spring means engaging said surfaces comprising .a .pair of elongate arms of curvilinear cross section extending transversely of said shaft,

each of said .armshaving .anopen side facing said socket. surface. and-an apex engagin said aft ."surf caJam aiconneotorimember extendn betwe n andintctccnnectingisaid,armgjfqr spaced; relation with said rear edges rest on said rear edges of said arms below the forward edges thereof but with..certain...of.said edgesparallel to each other;

certain edges of said arms substantially parallel to each other but with the rear edges of said arms below theforward edges thereof, whereby socket surface and said forward edges. are spaced from said socket surface ,prior to assembly of said knob on said shaft thereby to permit transverse fiexure of said arms by said shaft.

'5. In combination, a control knob having a shaft receiving socket including a flat side wall surface, a shaft received in said socket andjhaving a fiat surface. facing said flat socket surface, and spring means engaging said surfaces comprising a pair. of elongate arms, extending transversely of said shaft and .of substantially vshaped crossysecti'on with the open sides ofsald arms facing said socket surface-anda connector member extending between. and interconnecting said arms for maintaining said arms in spaced relation, with at least one edge of said V being substantially parallel to a corresponding. .edge of the other said V', the rear edge of eaohv' being at a lower level than the forward edge thereof, whereby said rear edges, engagesaid socket surface and said armsare free to flex transversely upon engagement of said shaft surface with the apices of said arms.

6'. In combination, a control knob having a shaft receiving socket including a fiat side wall surface, a shaft received in said socketand having a fiat surface. facing said fiat socket surface, and springmeans engaging said surfaces comprising a pair of elongate. arms extending transversely of said shaft and of substantially V- shaped cross section with the open sides of said arms facing said socket surface, and a connector member extending between said armsfor maintaining said arms in spaced relation, with certain of the edges, of said V..',s, substantially parallel but with. the. rear edge of each V at a lower level than the forward edgethereof whereby said rear edges engage. said socketsurface and said arms are free to. flex transversely upon engagement of said shaft surface with the apices of said arms, said connector member being connected with each of said armsiadiacent said rear edges to permit full freedom. of. flexure in the portions of said arms forwardly .of the. points of engagement .of said connector member.

-GEORGE.K. GREEN.

ReferencesnOited in the file of "this patent UNITED STATES PAIENTS 

